Low air-loss mattresses

ABSTRACT

A low air-loss mattress comprises a containment envelope enclosing two lengthwise extending inflatable side chambers each connected to receive air under pressure from a source and each connected to supply such air under pressure to one or more laterally extending inflatable air sacks positioned between the two side chambers. Each air sack is formed with a multiplicity of holes through which air can leave the mattress.

BACKGROUND OF THE INVENTION

This invention relates to low air-loss mattresses and beds therefor.

Low air-loss beds and mattresses are known which essentially consist ofa containment envelope of air permeable waterproofed material suppliedwith air under pressure and formed with a multiplicity of discrete holesthrough which air can leave the mattress. Such beds and mattresses areused in the treatment of patients at risk to the onset of skinmaceration and the formation of pressure ulcers.

It has been found with known air-loss beds that patients are at risks offalling particularly when getting onto and off from the bed. Also manyair-loss systems have limited facility for providing a profiled airpressure along the mattress length and for selectively changing thepressure of air within the mattress ad automatically maintaining thatselected air pressure.

It is also the case that in some air loss mattresses there is noprovision for being able to measure the pressure within the mattress indifferent areas so as to provide the benefit of variable pressureswithin the mattress.

SUMMARY OF THE INVENTION

The present invention sets out in one aspect to provide a low air-lossmattress which includes additional safeguards against a patient fallingand, in another aspect, a control system for selectively varying andautomatically maintaining a selected air pressure within the mattress.

According to the present invention in one aspect there is provided a lowair-loss mattress which comprises a containment envelope enclosing twoinflatable side chambers of an air impervious material extendinglengthwise of the mattress and each connected through a releasableconnector to receive air under pressure from a source and connected tosupply such air under pressure to a plurality of side-by-side inflatableair sacks of a permeable material extending laterally of the mattressand between the two side chambers, the arrangement being such that, wheninflated, the upper surface of each side chamber lies at or above theupper surface of the air sacks.

In a preferred arrangement, alternate air sacks are connected to receiveair under pressure from one side chamber, the other air sacks beingconnected to receive air under pressure from the other side chamber.Each releasable connector may include a restricted orifice whichoperates to regulate the flow of air to the respective air sack and thepressure of air within that air sack.

Means may be provided to retain the air sacks in side-by-side relation.This means may comprise a containment envelope for the air sacks whichcomprises upper and lower sheets joined together by a plurality oftransverse partitions to define elongate pockets into each of which oneof the air sacks is positioned. Other retention means may be employed,these including a series of straps attached to a lower sheet whichdefine loops into each of which one of the air sacks can be positioned.

Each side chamber may be supplied with air under pressure through amanifold conduit located within the containment envelope and includingconnectors attachable to inlet connections of the two side chambers. Theconnectors may comprise push fit connectors. Other forms of connectorsmay however be employed.

Means may be provided for interrupting sequentially the supply of airunder pressure to the two side chambers thereby alternately to increaseand decrease the pressure in each of the side chambers. This operationwill result in an alternating pressure listing between the air sacksbeing supplied with air by the respective chambers. Thus, each sidechamber may be independently supplied with air under pressure, thesesupplies being sequentially controlled as described.

The manifold conduit may be connected to the source of air underpressure through control apparatus including a microprocessor whichoperates selectively to vary the pressure of air supplied to themanifold and/or to maintain within the mattress a required air pressure.

Thus the pressure of air within the manifold and/or one or both sidechambers may be measured and relayed to the control apparatus, thelatter effecting an increase or decrease in air pressure in response toa detected difference between the selected and measured values.

The control apparatus may operate to vary a selected pressure by pre-satpercentages in response to a patient sitting up or lying an one side.The control apparatus may also be operable to supply on demand a maximumair pressure to the mattress to provide a firm setting for, for example,physiotherapy. The control apparatus may also be operable to deflate themattress by sucking air from its Interior in response, for example, to aneed for cardio pulmonary resuscitation. Furthermore the controlapparatus may operate to sound or display alarm automatically in theevent off for example, a loss or air pressure or electrical supply.

In another aspect, there is provided a low air-loss mattress whichincludes two lengthwise extending inflatable side chambers of animpervious material each connected to receive air under pressure from asource and each connected to supply such air to alternate ones of aplurality of inflatable air sacks of a permeable material which extendlaterally between the side chambers.

Each side chamber may extend along the entire length of the mattress ora part thereof. There may, therefore, be two or more individualinflatable side chambers extending along each side of the mattress, eachsuch side chamber being connected to the same source of air underpressure or to two or more different such sources.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only withreference to the accompanying diagrammatic drawings in which:

FIG. 1 is a perspective view of a mattress in accordance with theinvention with its containment, envelope partially removed;

FIG. 2 is a plan view from above partly in section of the low air-lossmattress shown in FIG. 1 with its containment envelope removed;

FIG. 3 is a section to an enlarged scale of a releasable connectionbetween a side chamber and an air sack of the mattress disclosed in FIG.1; and

FIG. 4 is a perspective view of a hospital or therapeutic bed fittedwith a micro-processor driven control apparatus for use with the lowair-loss mattress illustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The low air-loss mattress illustrated in FIGS. 1 to 3 comprises aquilted containment envelope which includes an outer layer 1 of, forexample, an ultra soft NYLON fabric to minimise skim friction and to aidpressure distribution, a second layer 2 of, for example, breathableurethane 2 to provide a barrier to liquids and bacteria whilstpermitting the passage of vapor, a third layer 3 of, for example, DACRONfibre fill to promote osmotic action of urethane and to encourage thedispersal of vapour through a wicking action and a fourth layer 4 of airpermeable fabric to reduce friction and to assist in the dispersal ofvapour.

The envelope has a integral foam underlay 5 to prevent a patient beingat risk during transportation or in the event of a power failure.

Contained within the envelope is an assembly of two lengthwise extendinginflatable side chambers 6 and a multiplicity of lateral air sacks 7.Typically eighteen air sacks are provided in a mattress for use byadults. Other numbers of air sacks could however be employed. As will beseen from FIG. 3, the air sacks 7 are connected to the side chambers 6through releasable connectors having restricted orifices 8 whosediameters may vary along the length of the mattress to provide aprofiled air pressure. Thus the orifices may be selected to provide afirmer pillow area and a softer heel area. As will be seen from FIG. 2,alternate air sacks are connected to one of the side chambers with theinterposing air sacks being connected to the other side chamber. Eachair sack is produced from a permeable material having a multiplicity ofholes 9 through which air can leave the mattress.

The air sacks 7 are positioned one within each of a plurality ofopen-end-distally extending pockets 10 formed in a retaining cover 11.The pockets 10 are formed between upper and lower sheets 12 of the cover11 and length of material 14 secured to these sheets.

Each side chamber is connected to receive air under pressure from acommon source via a manifold conduit 15. This conduit is in turnconnected to receive air under pressure through am outlet pipe 16 of amicroprocessor driven controller 17. This controller will be describedin greater detail below with reference to FIG. 3 of the drawings.

In an alternative arrangement, two outlet pipes 16 are provided, eachbeing connected to supply air under pressure to one of the sidechambers. Switching means may be provided sequentially to increase anddecrease the supply of air to the two chambers in an alternating senseto produce an alternating pressure system, for the mattress

The manifold conduit is includes a pair of male or female connectorsattachable to complementary connectors of the side chambers 6. The sideclambers are produced from an impervious material and are consequentlyeach at a higher pressure than that of the air sacks 7. When inflated,the upper surface of each side chamber lies at the level of or slightlyabove the air sacks 7.

In use, the several air pressure sacks 7 are supplied with air underpressure from the side chambers 6, this air replenishing the air whichis constantly leaving the sacks 7 through the holes 9. The pressure ofair within the individual sacks may differ depending upon the size oforifices 8 employed. The side chambers 6 are in turn supplied which airunder pressure from the manifold 15. Because, a mentioned previously,the side chamber, 7 are in use subjected to higher air pressures thanthat within the air sacks, they operate to provide a firm edge to eachmattress side to provide support to a patient when getting onto and offfrom the mattress. Also, these side chambers tend to cradle the patientto give a feeling of support.

As mentioned previously, the manifold conduit 15 is connected to receiveair under pressure via a microprocessor driver controller. Thiscontroller 17 is illustrated in FIG. 3 and is positioned between thesource of air pressure (e.g. a pump) and the mattress to be supplied.

For any give patient at-risk to pressure ulcers it is important that thepressure of air within the mattress is set at a value appropriate to theneeds of the patient. It is also extremely important that, onceselected, this pressure is not only maintained but is seen to bemaintained. To achieve this objective, a open-ended flexible tube 19 isconnected at one end to a pressure sensitive diaphragm or the likewithin the controller 17 and passes trough the outset pipe 16 to aposition conveniently midway along the length of the manifold conduit 15or, if required, to positions within one or each side chamber.Alternatively, the free end of the tube 19 may be positioned within thepipe 16 and not pass into the mattress. The pressure sensitive tube 19relays to the controller 17 the actual pressure supplied to or withinthe mattress and activates a comparator of the microprocessor toincrease or decrease the flow of air to the mattress through the pipe 16in the event that the required pressure differs from the measuredpressure.

The required pressure is sat by touch pads 21 on a control panel of thecontroller, one operating to increase the pressure and the other todecrease the pressure. The set pressure is displayed on a display 22.This display may take the form of a simple segmental coloured line whoselength increases or decreases with pressure; other forms of display may,however, be employed.

The control panel af the controller 17 also includes touch pads 23 toadjust the mattress pressure by preselected percentages for patients whoare sitting up or lying on one side. An additional touch pad 24 isoperated immediately to maximise the pressure within the mattress toprovide a firm setting for, for example, physiotherapy. The controllerfurther includes an audio and/or visual alarm which operates in theevent, for example, a loss of air pressure or electrical power.Furthermore, the controller provides a switch 25, which is operatedrapidly to deflate the mattress by sucking air from the mattress forpurposes of, for example, cardio pulmonary resuscitation.

The microprocessor driven controller may either be freestanding, may beprovided with clips for positioning on a therapeutic bed or may beformed internally with the bed, the control panel forming part of, forexample, the head or foot rest of a bed. This latter constructionenables a standard bed to be employed which is capable or receiving avariety of different low air-loss mattresses.

It will be appreciated that the foregoing is merely exemplary of lowair-loss mattresses and therapeutic beds therefor in accordance with theinvention and that modifications can be readily be made thereto withoutdeparting from the true scope of the invention as set out in theappended claims.

I claim:
 1. A low air-loss mattress which comprises two inflatable sidechambers of an impervious material extending lengthwise of the mattressand each connected to receive air under pressure from a source andconnected to supply such air under pressure to a plurality ofside-by-side inflatable air sacks of a permeable material which extendlaterally of the mattress and between the two side chambers, themattress being characterised in that the inflatable side chambers andair sacks are connected through releasable connectors and are enclosedwithin a containment envelope with alternate air sacks connected toreceive air under pressure only from one side chamber and the other airsacks connected to receive air under pressure only from the other sidechamber, the arrangement being such that, when inflated, the uppersurface of each side chamber lies at or above the upper surface of theair sacks.
 2. A mattress as claimed in claim 1 wherein each releasableconnector includes a restricted orifice.
 3. A mattress as claimed inclaim 1 wherein each side chamber is supplied with air under pressurethrough a manifold conduit located within the containment envelope andincluding connectors attachable to inlet connections of the two sidechambers.
 4. A mattress as claimed in claim 3 wherein the manifoldconduit is connected to the source of air under pressure through controlapparatus including a microprocessor which operates selectively to varythe pressure of air supplied to the manifold and/or to maintain withinthe mattress a required air pressure.
 5. A mattress as claimed in claim1 wherein means are provided for interrupting sequentially the supply ofair under pressure to the two side chambers to increase and decreasealternately the pressure in each of the side chambers.
 6. A mattress asclaimed in claim 1 wherein the containment envelope comprises upper andlower sheets joined together by a plurality of transverse partitions todefine elongate pockets within each of which is positioned one of theair sacks.